Questionnaires list filtering should be case neutral

[romaintailhurat]

When filtering a list of questionnaires, lowercase and UPPERCASE inputs should provide the same result.

Currently, we have the following behaviour:

1. say we have a list of questionnaire with titles containing the QNONREG string
2. the user types qnon and obtains a filtered list →
3. the user types QNON, the result list is empty →

With both input strings we should have the same list, the ones that we get in the 2. step.